Everyone knows they feel much better after a good night's sleep，but now scientists have discovered it can help you to live longer too.According to a study in the US，healthy sleeping habits mean men can live almost five years longer the chance of heart disease.
However，a study shows it's not just about how long you sleep；theof your sleep is important too.Dr Frank Qian said sleep must be restful.The researchers said that good sleep for adults depended on five basic factors：
•getting seven to eight hours of sleep each night；
•having trouble falling asleep no more than twice a week；
•having trouble staying asleep no more than twice a week；
•not using m to get to sleep；
•waking up feeling rested at least five days a week.
Each factor was given one point with a total of five points.The researchers looked at the results of a survey of 172，321 people in the US that measured their health habits， i sleep，over five years.They found that people who had all five points were l to live longer and lead healthier lives than those who had sleep difficulties.
According to The Sleep Charity，a good night's sleep can improve people's memory.Dr Qian admits that no one's sleep is p everyone has a late or restless night sometimes.However，he said， "Even from a young age，making sure they are sleeping tight...it can greatly b their overall long﹣term health."The study was based on people reporting their own sleep habits rather than recording them scientifically，so this may have affected the results and more research is needed.
